Abstract

Since the initial observations (1,2) of the effect of 2,3 diphosphoglycerate (2,3 DPG) upon the oxygen affinity of hemoglobin, considerable interest has focussed on the importance in the gas exchange process (3,4) of this species and other organic phosphates. This paper summarizes a theoretical analysis of the influence of 2,3 DPG on O2 transport in hemoglobin solutions. The physical system analyzed is the same as that used in previous treatments of hemoglobin-facilitated oxygen transfer (5). A thin film of solution separates two phases containing differing partial pressures of oxygen (PO2). Hemoglobin, although mobile, is constrained to remain within the liquid film. As a result of 02-Hb interactions, the diffusion of O2 from the high to the low pO2 boundary induces a parallel diffusion of oxyhemoglobin. If 2,3 DPG is present, there are gradients in the concentrations of free and of hemoglobin-bound 2,3 DPG as a result of the gradients in oxy- and deoxyhemoglobin and preferential binding of 2,3 DPG to the latter (6). In this study, the concentrations of free and bound 2,3 DPG were taken to be constant across the film.